Table 2.

Neuropsychological tests of attention and executive functions used in this study

Task group	Test	Task description	Performance index	Measured functions	Origin
Digit spans	Digit span forward	Digit sequences of 3 to 8 digits are read out and have to be reproduced in the presented order	Number of correctly remembered digits	Short‐term memory [Kaufman et al, 1991]	Wechsler Memory Scale Revised, German version [Härting et al., 2000]
	Digit span backward	Digit sequences of 3 to 8 digits are read out and have to be reproduced in inverse order	Number of correctly remembered digits	Short‐term memory, data manipulation [Lezak, 1995]
	Digits difference score	–	Calculated: Digit span forward ‐ digit span backward	Data manipulation [Wager and Smith, 2003]
Trail‐making tests (TMT)	TMT part A	25 numbers on a sheet of paper have to be connected by pencil in ascending order	Time to completion	Attention, visual searching, psychomotor speed [Shum et al., 1990]	Compendium of neuropsychological tests [Spreen and Strauss 1998]
	TMT part B	Same as TMT A, but numbers and letters have to be alternated in ascending order	Time to completion	Attention, visual searching, psychomotor speed, set shifting [Shum et al., 1990]
	TMT difference score	–	Calculated: TMT part B ‐ part A	Set shifting [Spreen and Strauss, 1998]
Stroop tests	Stroop test part II	Colored rectangles are presented. Subjects have to name the colors.	Time to completion	Color perception, color naming, speed of processing [MacLeod, 1991]	[Stroop, 1935]; German version: Nürnberger Altersinventar (Nuremberg Gerontopsychological Inventory) [Oswald and Fleischmann, 1997]
	Stroop test part III	Colored rectangles with conflicting color words printed on them are presented. Subjects have to name the colors of the rectangles.	Time to completion	Color perception, color naming, speed of processing, response inhibition [MacLeod, 1991]
	Stroop difference score	–	Calculated: Stroop test part III ‐ part II	Response inhibition [Zajano and Gorman, 1986]